A bearing arrangement which is generally of the above-described type is disclosed in German Patent Specification No. 2257158. In such an arrangement, the back-pressure forces emanating from the screws are conducted through a gear arrangement and are then absorbed by an axial bearing which is screw-connected to the gear housing. The axial bearing is, itself, disposed in a housing which is mounted on an intermediate plate-screw-connected to the gear housing.
The back-pressure of the screws is transmitted from the back-pressure bearing to the gear housing through the intermediary of the intermediate plate in the event of longitudinal expansion of the adjustment bolts. The provision of a free space or gap on the opposite side of the gear housing, that is to say, between the gear housing and the housing for the extrusion device, does not prevent the back-pressure forces of the screws from entering the gear housing when longitudinal expansion of the tension rods or adjusting bolts occurs. This is because the housing of the back-pressure bearing is connected to the gear housing through the intermediary of the intermediate plate. If the back-pressure forces enter the gear housing, the housing becomes distorted and, in consequence, the bearings for the various gear wheels disposed therein also become slightly deformed. This impairs the meshing between the toothed wheels and pinions and causing increased wear on the toothed wheels. In addition, back-pressure bearings which are flange-mounted on the gear housing increase the overall length of the structure and make the gear more expensive.
It is also disadvantageous to conduct the back-pressure forces of the screws initially through the gear so that they then return through the gear housing to the housing of the extrusion device through the intermediary of spacer bolts, tension rods or adjustment bolts. This measure makes the bearing arrangement very complex and extremely expensive.